CVE-2023-40033
Server-Side Request Forgery via Avatar upload in flarum
Flarum is an open source forum software. Flarum is affected by a vulnerability that allows an attacker to conduct a Blind Server-Side Request Forgery (SSRF) attack or disclose any file on the server, even with a basic user account on any Flarum forum. By uploading a file containing a URL and spoofing the MIME type, an attacker can manipulate the application to execute unintended actions. The vulnerability is due to the behavior of the intervention/image package, which attempts to interpret the supplied file contents as a URL, which then fetches its contents. This allows an attacker to exploit the vulnerability to perform SSRF attacks, disclose local file contents, or conduct a blind oracle attack. This has been patched in Flarum version 1.8.0. Users are advised to upgrade. Users unable to upgrade may disable PHP's allow_url_fopen which will prevent the fetching of external files via URLs as a temporary workaround for the SSRF aspect of the vulnerability.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Server-Side Request Forgery via Avatar upload in flarum
Flarum is an open source forum software. Flarum is affected by a vulnerability that allows an attacker to conduct a Blind Server-Side Request Forgery (SSRF) attack or disclose any file on the server, even with a basic user account on any Flarum forum. By uploading a file containing a URL and spoofing the MIME type, an attacker can manipulate the application to execute unintended actions. The vulnerability is due to the behavior of the intervention/image package, which attempts to interpret the supplied file contents as a URL, which then fetches its contents. This allows an attacker to exploit the vulnerability to perform SSRF attacks, disclose local file contents, or conduct a blind oracle attack. This has been patched in Flarum version 1.8.0. Users are advised to upgrade. Users unable to upgrade may disable PHP's allow_url_fopen which will prevent the fetching of external files via URLs as a temporary workaround for the SSRF aspect of the vulnerability.
- Record
CVE-2023-40033- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N - Weakness
- CWE-918
- Updated
- 2026-11-02
EUVDEUVD-2023-2223
Flarum is an open source forum software. Flarum is affected by a vulnerability that allows an attacker to conduct a Blind Server-Side Request Forgery (SSRF) attack or disclose any file on the server, even with a basic user account on any Flarum forum. By uploading a file containing a URL and spoofing the MIME type, an attacker can manipulate the application to execute unintended actions. The vulnerability is due to the behavior of the intervention/image package, which attempts to interpret the supplied file contents as a URL, which then fetches its contents. This allows an attacker to exploit the vulnerability to perform SSRF attacks, disclose local file contents, or conduct a blind oracle attack. This has been patched in Flarum version 1.8.0. Users are advised to upgrade. Users unable to upgrade may disable PHP's allow_url_fopen which will prevent the fetching of external files via URLs as a temporary workaround for the SSRF aspect of the vulnerability.
- Record
EUVD-2023-2223- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-67c6-q4j4-hccg
Flarum vulnerable to LFI and Blind SSRF via Avatar upload
Impact
The Flarum forum software is affected by a vulnerability that allows an attacker to conduct a Blind SSRF attack or disclose any file on the server, even with a basic user account on any Flarum forum. By uploading a file containing a URL and spoofing the MIME type, an attacker can manipulate the application to execute unintended actions. The vulnerability is due to the behavior of the intervention/image package, which attempts to interpret the supplied file contents as a URL, which then fetches its contents. This allows an attacker to exploit the vulnerability to perform SSRF attacks, disclose local file contents, or conduct a blind oracle attack.
Patches
This has been patched in Flarum v1.8.
Workarounds
As a temporary workaround for the SSRF aspect of the vulnerability, one can disable PHP's allow_url_fopen which will prevent the fetching of external files via URLs.
Credits
Adam Kues - Assetnote
- Record
GHSA-67c6-q4j4-hccg- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N - Weakness
- CWE-98, CWE-918
- Updated
- 2026-11-02
NVD
Flarum is an open source forum software. Flarum is affected by a vulnerability that allows an attacker to conduct a Blind Server-Side Request Forgery (SSRF) attack or disclose any file on the server, even with a basic user account on any Flarum forum. By uploading a file containing a URL and spoofing the MIME type, an attacker can manipulate the application to execute unintended actions. The vulnerability is due to the behavior of the intervention/image package, which attempts to interpret the supplied file contents as a URL, which then fetches its contents. This allows an attacker to exploit the vulnerability to perform SSRF attacks, disclose local file contents, or conduct a blind oracle attack. This has been patched in Flarum version 1.8.0. Users are advised to upgrade. Users unable to upgrade may disable PHP's allow_url_fopen which will prevent the fetching of external files via URLs as a temporary workaround for the SSRF aspect of the vulnerability.
- Record
CVE-2023-40033- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N - Weakness
- CWE-918
- Updated
- 2026-11-02
OSV
Server-Side Request Forgery via Avatar upload in flarum
Flarum is an open source forum software. Flarum is affected by a vulnerability that allows an attacker to conduct a Blind Server-Side Request Forgery (SSRF) attack or disclose any file on the server, even with a basic user account on any Flarum forum. By uploading a file containing a URL and spoofing the MIME type, an attacker can manipulate the application to execute unintended actions. The vulnerability is due to the behavior of the intervention/image package, which attempts to interpret the supplied file contents as a URL, which then fetches its contents. This allows an attacker to exploit the vulnerability to perform SSRF attacks, disclose local file contents, or conduct a blind oracle attack. This has been patched in Flarum version 1.8.0. Users are advised to upgrade. Users unable to upgrade may disable PHP's allow_url_fopen which will prevent the fetching of external files via URLs as a temporary workaround for the SSRF aspect of the vulnerability.
- Record
CVE-2023-40033- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N - Weakness
- CWE-918
- Updated
- 2026-11-02
OSVGHSA-67c6-q4j4-hccg
Flarum vulnerable to LFI and Blind SSRF via Avatar upload
Impact
The Flarum forum software is affected by a vulnerability that allows an attacker to conduct a Blind SSRF attack or disclose any file on the server, even with a basic user account on any Flarum forum. By uploading a file containing a URL and spoofing the MIME type, an attacker can manipulate the application to execute unintended actions. The vulnerability is due to the behavior of the intervention/image package, which attempts to interpret the supplied file contents as a URL, which then fetches its contents. This allows an attacker to exploit the vulnerability to perform SSRF attacks, disclose local file contents, or conduct a blind oracle attack.
Patches
This has been patched in Flarum v1.8.
Workarounds
As a temporary workaround for the SSRF aspect of the vulnerability, one can disable PHP's allow_url_fopen which will prevent the fetching of external files via URLs.
Credits
Adam Kues - Assetnote
- Record
GHSA-67c6-q4j4-hccg- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N - Weakness
- CWE-918, CWE-98
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
flarum/corePackagist |
before 1.8.0 | 1.8.0 |
flarum/frameworkPackagist |
before 1.8.0 | 1.8.0 |
flarum/corePackagist |
before 1.8.0, plus listed versions v0.1.0-betav0.1.0-beta.10v0.1.0-beta.11v0.1.0-beta.11.1v0.1.0-beta.12 Show 38 moreShow lessv0.1.0-beta.13v0.1.0-beta.14v0.1.0-beta.14.1v0.1.0-beta.15v0.1.0-beta.16v0.1.0-beta.2v0.1.0-beta.3v0.1.0-beta.4v0.1.0-beta.5v0.1.0-beta.6v0.1.0-beta.7v0.1.0-beta.7.1v0.1.0-beta.7.2v0.1.0-beta.8v0.1.0-beta.8.1v0.1.0-beta.8.2v0.1.0-beta.9v1.0.0v1.0.1v1.0.2v1.0.3v1.0.4v1.1.0v1.1.1v1.2.0v1.2.1v1.3.0v1.3.1v1.4.0v1.4.1v1.5.0v1.6.0v1.6.1v1.6.2v1.6.3v1.7.0v1.7.1v1.7.2 |
1.8.0 |
flarum/frameworkPackagist |
before 1.8.0, plus listed versions v0.1.0-betav0.1.0-beta.10v0.1.0-beta.11v0.1.0-beta.11.1v0.1.0-beta.12 Show 36 moreShow lessv0.1.0-beta.13v0.1.0-beta.14v0.1.0-beta.14.1v0.1.0-beta.15v0.1.0-beta.16v0.1.0-beta.2v0.1.0-beta.3v0.1.0-beta.4v0.1.0-beta.5v0.1.0-beta.6v0.1.0-beta.7v0.1.0-beta.7.1v0.1.0-beta.7.2v0.1.0-beta.8v0.1.0-beta.8.1v0.1.0-beta.8.2v0.1.0-beta.9v1.0.0v1.0.1v1.0.2v1.0.3v1.0.4v1.1.0v1.1.1v1.2.0v1.2.1v1.3.0v1.3.1v1.4.0v1.5.0v1.6.0v1.6.1v1.6.2v1.6.3v1.7.0v1.7.1 |
1.8.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2023-40033 is a high vulnerability (CVSS 7.1) in Flarum, published August 16, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.50%, the 43rd percentile. Fixed in flarum/core 1.8.0.
References
github.com/flarum/framework/security/advisories/GHSA-67c6-q4j4-hccg
nvd.nist.gov/vuln/detail/CVE-2023-40033